MusiCuddle is a system to calm the symptoms of patients with mental instability who repeat stereotypical utterances. The system presents a short musical phrase whose first note is the same as the fundamental pitch (F0) of a patient’s utterances. We performed a case study to investigate how a patient’s behaviors changed with MusiCuddle. The results suggested that the phrases presented by MusiCuddle may provide patients with an opportunity to stop repeating stereotypical utterances. Then, we added a vocoder function to MusiCuddle so that patients would be able to attend to the music more. We examined whether the mood of university students changed or not according to music presented with the vocoder function. We found significant differences between major harmonies and minor harmonies for the “cheerful” and “negative” moods. Namely, when a person’s voice is combined with cheerful sounds, he/she can become cheerful. However, when we conducted a case study to expect a patient’s repetitive utterances changed or stoped by the sound from the MusiCuddle with the vocoder, the participant’s utterances did not change. We discussed reasons of the result from an aspect of characteristic of a patient according to a cause disease of dementia.